As of early Wednesday evening, officers had gone door to door to several hundred houses in the search for Taylor Rose Williams.

"We are very concerned, but we are going to search and we're going to continue to search throughout the night," Jacksonville Sheriff's Office Chief of Investigations T.K. Waters said at a 5:15 p.m. news briefing.

Waters said the girl's mother, Brianna Williams, had been taken downtown to police headquarters, where she was being questioned. Waters said the mother, who has not asked for a lawyer, and entire family, including the girl's father, who is out of state, are cooperating.

Police said they were told Taylor was last seen around midnight Wednesday in her house on Ivy Street in Brentwood. Police said they were called at 7:22 a.m. to the Ivy Street home, where Williams said she had woken up, and found her daughter missing from her room and the back door of the home unlocked.

The Navy confirmed to News4Jax that Taylor's mother, Williams, is a petty officer first class at the Tactical Operations Center at Naval Air Station Jacksonville.

Waters said police have no idea where the child is, but police will continue to search and the investigation remains a missing persons case.

"We are going to investigate this case. We're going to be very thorough in how we do it," he said. "We want Taylor at home safely."

The FDLE issued a missing child alert at 9:21 a.m. and an Amber Alert for Taylor went out about 11:30 a.m. on cellphones, billboards, Florida Department of Transportation message boards and to all law enforcement officers across the state.

“It's very urgent that we find her as quickly as possible,” Waters said at 10:30 a.m. news briefing. “We'll work until we can't work anymore.”

Taylor is described as 3 feet tall, weighing 50 pounds with brown eyes and black hair. She was last seen wearing a purple shirt and pink pajama pants when she went to bed.

Taylor is believed to be in danger because of her age, Waters said.

He said investigators are not ruling out any possibilities at this point, including that Taylor left the home on her own or was abducted.

"We're pulling out all the stops," Waters said.

Authorities said there was no sign of foul play in the house, and everything in the house looked normal. By Wednesday afternoon, a tow truck removed a car from the family's home. Around 4:50 p.m., officers took down police tape in Brentwood and secured the house.

Police also confirmed they were also searching the Southside Villas apartment complex on Southside Boulevard, where the family of Taylor lived before moving to Ivy Street. Dozens of officers were seen searching and the JSO dive team arrived just after 3 p.m. at the complex. Soon after, officers could be seen searching garbage that had been removed from the complex.

K-9 officers and mounted officers could be seen helping in the search.

News4Jax crime and safety analyst Ken Jefferson said use of the mounted unit in a neighborhood is rare.

“That shows you the urgency of what's going on," Jefferson said. "Investigators will be looking at the adults in the home and what happened leading up to her disappearance “Our priority right now is to pray for the safety of this child and her being found.”

Jacksonville Fire and Rescue brought a Command Center vehicle to the Brentwood scene Wednesday morning. The Sheriff's Office said drone units and the air unit were also being used in the search.

Police, as well as neighbors, searched into the night. One community member, Kevin Weston, who showed up to help in the search, said the little apparent progress has been frustrating.

"None of the stories are adding up," Kevin Weston said. "It's just really not making sense and it's kind of bothering us."

A Brentwood neighbor told News4Jax that she saw children's toys, but never saw a child at the home where police said the girl was reported missing.

"I haven’t seen her the whole time," neighbor Brianna South said. "I knew they moved in and I saw the kids’ stuff, but I never actually seen the kids."

South continued: "I saw the kids' stuff but not her."

As the search continues, anyone who might have seen Taylor or might know where she is should call the Jacksonville Sheriff's Office immediately at 904-630-0500.